The proposed research will investigate the neural basis of one aspect of sentence comprehension using PET scanning techniques. The particular aspect of sentence comprehension to be studied will be the ability to assign the syntactic structure of a sentence. Subjects will be asked to match sentences with complex syntax to pictures, ark other, simpler, sentences to similar pictures, while PET activity is measured. The difference in activation patterns between the complex and simple sentences will be taken as an indication of the areas of brain involved in establishing the syntactic form of the more complex sentences. This research will complement previous work that has investigated the neural basis of syntactic comprehension by correlating deficits in this ability with acquired brain lesions. It will provide a better idea of the neural loci that carry out this function, and thus should be useful in evaluating the neural basis of disorders of this ability in brain- damaged patients.